spark plugs won't work

[gixxer]

i have a 1977 mercury 200 thunderbolt ignition 20 hp. the book calls for it to run the champion 833 spark plug, which is the type that doesn't have a gap pronge on the back hence the book calls for no gap specs. put the plugs in and it will not crank, if it does it's only for about 1 to 2 seconds. i just bought the boat a week ago and rebuilt the carb and put in the new plugs. after i couldn't get it to run, i went and bought a set of the plugs that were in it when i got it which are the type that have to be gapped. i put these in gapped at .40 and the motor fired right over, though it ran very rough. i then closed the gap on the plugs to .25 and tried it again. this time it ran alot smoother. does this mean the ignition coils are weak or going bad? looking for any input

 

[Hooty]

Re: spark plugs won't work

You need a manual to verify this but the ignition spark should jump a 7/16" gap with just the starter spinning the engine. To test this you need a Spark Tester. They can be had at a auto supply store. It should be a strong, bright blue spark.<br />Get the manual first.<br /><br />c/6<br /><br />Hooty

 

[rickdb1boat]

Re: spark plugs won't work

Just as a side note, your Gap should be .030 !